9
I/O
available for download on the website: www.weg.net.
9.5 FREQUENCY INPUT
A frequency input consists of a fast digital input able to convert the frequency of the pulses in the input into a
proportional signal with 15-bit resolution. After the conversion, this signal is used as an analog signal for frequency
reference, process variable, for example.
According to the block diagram of Figure 9.5 on page 9-10, the signal in frequency is converted into a digital
quantity in 15 bits by means of the block ”Calc. Hz / %”, where parameters P248 and P250 define the input signal
frequency band, while parameter P022 shows the frequency of the pulses in Hz.
FI (%)
FI (Hz)
FI(Hz) - P022
P245
Calc. Hz / %
P250
P248
100
(%)
(Hz)
Signal FI
(via DIx)
Offset
FI - P249
Gain
FI - P247
Filter
Function
FI - P246
Value FIx
(internal)
Figure 9.5: Block diagram of frequency input - FI (DIx)
Digital input DIx is pre-defined for frequency input via parameter P246, with operating capacity in a wide band from
1 to 3000 Hz.
Parameters P248 and P250 determine the operation range of the frequency input (FI), while parameters P249 and
P247 determine the offset and gain, respectively, according to with the equation:
FI =
FI (Hz) - P248
P250 - P248
x (100 %) + P249
x P247
For example, FI = 2000 Hz, P248 = 1000 Hz, P250 = 3000 Hz, P249 = -70.0 % and P247 = 1.000, thus:
FI =
2000 - 1000
3000 - 1000
x (100 %) - 70 %
x 1.000 = -20.0 %
The value FI = -20.0 % means that the motor will run in the opposite direction with a reference in module equal
20.0 % of P134, with the function of the FI signal for ”Frequency Reference” (P221 = 4).
When P246 = 3, the digital input DI3 is defined for frequency input, regardless the value of P265, with operating
capacity in the band from 0 to 3000 Hz in 10 Vpp.
The time constant of the digital filter for the frequency input is defined by means of parameter P245.
P022 - FI Value in Hz
Range: 0 to 3000 Hz
Properties: ro
Description:
Value in hertz of the frequency input FI.
9-10 | Micro Mini Drives
To Next Page
Loading...
